The logistics, certainly, is an issue, I'm not sure about the factory capability. Now, sure, if they are making tanks, they obviously aren't using those factories for something else, but (without knowing much about Russia's manufacturing capabilities), you don't need a factory that's equipped to make more modern tanks if you are only making something from decades earlier. For example, modern MBT armour is a lot fancier than the simple steel plate that used to be used. By comparison, the British Sten Gun in WW2 could be make in a simple garage workshop, and didn't necessarily need to tie up space in a well equipped factory.
Now, there's probably components of modern tanks than can be made in factories without sophisticated machines, though.